HOMOSEXUALS CHOOSE to be gay. If they wanted, they could be straight. Therefore, they don’t constitute a class of people in need of court rulings or legislative action protecting their rights or relationships. That’s what Larry Houston, a Somerville resident who describes himself as a "former homosexual," tells Massachusetts representatives and senators during weekly visits to the State House, at which he urges them to back an amendment to the state constitution barring any legal recognition of same-sex relationships.

Since last fall — when the legislature was first scheduled to consider the amendment at a constitutional convention that was eventually postponed to February 11 — Houston has spent at least one day a week paying visits to Beacon Hill lawmakers to tell them his story: he once engaged in homosexual acts, but not anymore. He once identified as homosexual, but now, he no longer believes what he calls "the lie of homosexuality" — i.e., that he was born gay.

Houston learned the advocacy ropes by tagging along with the Massachusetts Family Institute (MFI), one of the most active groups opposed to civil-marriage rights for same-sex couples in the state. When Houston heard through what he terms the "ex-gay grapevine" that MFI had enlisted former homosexuals from Florida to testify at an April 2003 hearing on the constitutional amendment, he called the organization to join the cause. By September, he was accompanying MFI lobbyist Evelyn Reilly on sessions with legislators, during which he served as "living testimony" to the "fact" that sexual orientation can change.

Two months later, Houston branched out on his own because the MFI sessions conflicted with his work schedule. Now he visits the State House solo, talking to any legislator or legislative aide who will listen. He carries a briefcase stuffed with papers to leave in legislators’ mailboxes and offices — copies of his essays on homosexuality, which say it’s "detrimental to many of those individuals who pursue it and to the society as a whole," as well as articles from the Boston Globe (I WAS INFECTED NEEDLESSLY), the New York Times (GAYS RESPOND: ‘I DO,’ ‘I MIGHT’ AND ‘I WON’T’), and the Washington Post (PARTWAY GAY? FOR SOME TEEN GIRLS, SEXUAL PREFERENCE IS A SHIFTING CONCEPT). Every week, he prints dozens of pages of documentation on a broken laser printer, painstakingly feeding pages into the machine by hand. It can take him eight hours to print 200 copies — one for each legislator. But he does it anyway to ensure that House and Senate members have "some background" while weighing the gay-marriage issue. He’s become such a familiar face that aides often call out "Hi, Larry" when passing him in the halls, or "Take it easy, Larry" when accepting his materials. By now, he’s known to many at the State House as "that former homosexual" — a notoriety he embraces. As he readily admits, "I’m the token ex-gay guy in this debate. I don’t mind."

He doesn’t mind, that is, as long as people are listening.

THE MODERN "ex-gay" movement dates back to 1973, with the founding of Love in Action, the first ministry to seek to "cure" people of homosexuality. Three years later, it was joined by Exodus International, a Christian organization promoting "freedom from homosexuality through the power of Jesus Christ," which now claims more than 135 ministries in 17 countries. Other prominent groups include the National Association for Research and Therapy of Homosexuality, and Homosexuals Anonymous, which offers a 14-step program to become straight.

For years, these ministries operated below the radar of public consciousness, including that of gay-rights organizations. But all that changed on July 13, 1998, when a full-page ad appeared in the New York Times. The ad — featuring Anne Paulk, billed as a wife, mother, and former lesbian — claimed that homosexuals can go hetero by accepting Jesus Christ. Similar ads in USA Today and the Washington Post captured additional media attention.

Today, now that the movement is more visible, it has become an object of open derision among gay activists.This is partly because of its close ties to right-wing organizations like the Family Research Council, Concerned Women of America, and Focus on the Family — many of the same national groups pouring money into Massachusetts to fight civil-marriage rights for same-sex couples. And it’s partly because of the hypocrisy among some of the movement’s leaders. In 1978, the two Exodus founders, Gary Cooper and Michael Bussee, left the effort (and their wives) after they fell in love. In the early ’90s, they took to the talk-show circuit to blast ex-gay ministries as a "fraud." The most famous fall from grace involved John Paulk — the husband of poster girl Anne — who headed the ex-gay ministry Focus on the Family (FOF) and promoted his own blissful marriage in the pages of major news outlets. In September 2000, while he was traveling on the FOF-sponsored Love Won Out tour, Paulk got caught in a Washington, DC, gay bar called Mr. P’s by gay-rights activist and author Wayne Besen, who photographed Paulk running down the street.

Despite these high-profile embarrassments, the movement keeps going. Its basic premise holds that sexual orientation is not an immutable characteristic, like race or gender, and therefore doesn’t warrant legal protection. The idea that heterosexuality is a choice might strike the straight people reading this as bizarre — chances are you never consciously decided to lust after the opposite sex. Not surprisingly, the notion that homosexuality is a choice has met with scorn from gay-rights groups. Says Jason Cianciotto, a policy analyst at the National Gay and Lesbian Task Force (NGLTF), in New York, "That anybody would choose to be gay in light of all the evidence showing how difficult it is to be gay in America is preposterous." That someone would choose to be called a "fag," to get beat up in school, or to be kicked out of their parents’ homes defies common sense. He adds, "Basic logic demands the question ‘How could you possibly say that?’"

But Larry Houston doesn’t hesitate to answer. People may not be able to control their attractions to those of the same sex, he says, but they can choose whether or not to follow up on those attractions. "You may have attractions. Your choice is, ‘Do I act on them?’" Besides, he points out, "Science has not proven that homosexuality is genetic."

It’s clear from interviews with Houston that he believes what he says. He comes across as sincere, up-front, willing to answer anything. He may even reveal too much. Talking about his homosexual trysts, he says he’s "thankful" he didn’t have many because "there’s pleasure in it." He continues, "The more you have, the more you want to repeat them.... I didn’t have many, so I don’t have many tapes to replay in my mind." He’s also pleasant and affable — indeed, he doesn’t like the "antagonistic" rhetoric of some fellow anti-gay-rights activists. All of which makes him a compelling figure.

HOUSTON IS sitting at a table outside the State House cafeteria, counting a stack of papers he plans to distribute to legislators. It’s just two weeks before House and Senate members will convene for the February 11 constitutional convention. "Did you see this?" Houston asks me. He shows me the January 20 front page of the Globe’s Living section, which is dominated by a photograph of two teenage boys, their faces pressed together, their arms wrapped around each other. The headline reads HOPE FOR THE FUTURE. Beneath the photo is an article describing how the 16- and 17-year-old boys — like many young gay and lesbian pairs — are looking forward to their wedding now that the Massachusetts Supreme Judicial Court has ruled that same-sex couples have a constitutional right to marry. Houston tells me the piece made him cry.

"There’s not one word of concern," he says. "Not one word of warning about the consequences of homosexual behavior. Not one word of caution about 16-year-olds making wedding plans.... This [article] sends a message to 12- and 13-year-olds. If you think you’re gay, try it out."

To counter this "journal activism,"as he calls it, Houston has written his own essay on homosexuality and adolescence for legislators that blasts "the homosexual advocates’ ‘adult motivations’ for gaining public sympathy for legalization of same-sex unions, with little regard for adolescents." He spent five days researching and writing the six-page handout, which is replete with quotes from studies about homosexual behavior among youths.

As Houston walks through the labyrinthine corridors of the State House, he exudes quiet determination. At 46, he is lean and rangy, with an elongated face and giant, square-framed glasses. He dresses in casual, yet conservative clothes — khaki pants, short-sleeved shirts, dark-colored ties. He has a genial, open demeanor. And when he enters legislators’ offices, he takes a deferential approach. He quietly slips materials into mailboxes; he cordially asks for a few minutes of attention. His politeness tends to conciliate people, who offer him wide smiles, hearty "Good mornings," even the occasional "How’s it going, Larry?"

On this Tuesday, Houston visits 15 legislators’ offices that make up his list of "regulars." They include such politically diverse representatives as Shrewsbury Republican Karyn Polito and Boston Democrat Marie St. Fleur. Although Houston has met most of the 15 legislators once — and has refrained from asking their positions on gay marriage and the constitutional amendment — he tries to influence them by wooing their top aides. After four months of office calls, he enjoys a rapport with many of them. As he describes it, "Would you write off someone who visits your office every week?"

Typically, these visits are amiable and short. At the office of Senator Brian Lees, the East Longmeadow Republican and Senate minority leader who moved to adjourn the July 2002 constitutional convention before it could consider an anti-gay amendment, Houston greets aide Daniel Conley with a handshake before launching into his complaints about the January 20 Globe article. He then offers his handout and emphasizes some key points — "A lot of teens try same-sex sexual activity, but grow out of it." Through it all, Conley, a tall, friendly man, says little. At one point, he tells Houston that he’ll put the materials in "the red book," a 50-plus-page folder of essays on homosexuality that Houston delivered to House and Senate leaders last fall.

The conversation lasts no more than three minutes, and it’s replayed nearly verbatim with most of the five aides whom Houston sees today. But every so often, he gets to debate. Dan Sullivan, the aide for Representative David Flynn, a Bridgewater Democrat and House dean, leans against his desk as he listens to Houston complain about the Globe article. When Houston bemoans the article’s "wrong message" and asserts that homosexuality is "about behavior, not identity," Sullivan interjects, "I think the jury is still out on that."

"No studies so far have shown that there is a gay gene," Houston responds.

"Until that’s determined," Sullivan suggests, "we have to deal with the fact that gay people are treated differently. That’s one reason people in this building are having this discussion about gay marriage." Sullivan then launches into a 10-minute monologue, during which he tells Houston that his boss Flynn "is supporting civil unions," but not gay marriage. "The representative is trying to meet both sides halfway," Sullivan says. "He’s trying to appease the gay community and not discriminate, yet he also understands concerns from religious groups." As Sullivan continues — touching upon the "stacks of e-mails virulently against the SJC decision" that Flynn’s office has received — Houston jiggles coins in his pocket. He taps his foot on the floor. Eventually, he makes a statement.

The only reason, he argues, that Massachusetts has to discuss same-sex marriage is "because gay advocates are pushing for something." He adds, "But who is asking? It’s a group of people defined by their behavior. This is not about rights."

"Still," Sullivan counters, "it’s difficult to have a homosexual couple come in to the representative’s office and for me to say, ‘I don’t believe that you’re equal.’"

The exchange goes on like this, back and forth, in circles, for 45 minutes. Finally, Sullivan likens the issue of gay marriage to that of abortion: "This whole debate has no real answers," he says. "It will rage on for a long time, regardless of what this legislature does." He then shakes Houston’s hand and thanks him for his "hard work."

"I’ll see you next week," Houston calls back. As he walks away, he marvels at how long the exchange has lasted. When I point out that it doesn’t appear Flynn is sympathetic to his ultimate message, he shrugs and says, "I’m taking a page from the gay advocates’ playbook. It’s about education."